Ultrasonic signal converter

Abstract

An ultrasonic device including a piezoelectric vibrator for converting an electric signal. The piezoelectric vibrator consists of a pillar-like piezoelectric ceramic and a pair of electrodes, A and B, positioned thereon on both end surfaces, ZA and ZB respectively, perpendicular to the polarization axis of the piezoelectric ceramic. The electrode A consists of at least two parts, namely electrodes A1 and A2, such that the electrodes A1 and A2 are not connected to each other. The electrode B consists of at least two parts, namely electrodes B1 and B2, such that the electrodes B1 and B2 are not connected to each other. If the ultrasonic signal converter is connected to a circuit X through the electrodes A1 and A2 and a circuit Y through the electrodes B1 and B2, then when a high-frequency electric signal S1 with a voltage V1 is applied from the circuit X to the piezoelectric ceramic, the piezoelectric vibrator can be vibrated effectively at a frequency, almost the same as the resonance frequency of the piezoelectric ceramic. This vibration of the piezoelectric vibrator is converted to an electric signal S2 with a voltage V2 having almost the same frequency as the resonance frequency of the piezoelectric ceramic. The electric signal S2 is then delivered toward the circuit Y. Thus, the ultrasonic signal converter makes it possible to convert an electric signal and an acoustic vibration to each other with a large efficiency.

What is claimed is: 
     
       1. An ultrasonic device for transducing an electric signal comprising: a pillar-like piezoelectric ceramic with a cylindrical shape such that the ratio of lengths between diameter and longitudinal directions is nearly equal to 1, said piezoelectric ceramic having two end surfaces, ZA and ZB, running perpendicular to the polarization axis of said piezoelectric ceramic; and   means for transducing an electric signal consisting of a first transducer element comprising at least two electrodes A1 and A2 forming an input pair, and a second transducer element comprising at least two electrodes B1 and B2 forming an output pair,   said electrodes A1 and A2 being formed on said surface ZA such that said electrodes A1 and A2 are not connected to each other and are separated by a line dividing the area of said surface ZA nearly at the rate of 1 to 1 and corresponding to diameter of said surface ZA,   said electrodes B1 and B2 being formed on said surface ZB such that said electrodes B1 and B2 are not connected to each other and are separated by a line dividing the area of said surface ZB nearly at the rate of 1 to 1 and corresponding to diameter of said surface ZB,   said piezoelectric ceramic, said electrodes A1, A2, B1 and B2 forming a piezoelectric vibrator,   said first transducer element receiving a high-frequency electric signal S1 with a voltage V1 from the outside, and causing said piezoelectric vibrator to vibrate at a frequency, almost the same as the resonance frequency of said piezoelectric ceramic,   said second transducer element transducing the acoustic vibration of said piezoelectric vibrator to an electric signal S2 with a voltage V2 having almost the same frequency as said resonance frequency, and delivering said electric signal S2 outside.   
     
     
       2. A device as defined in claim 1 further comprising: a load resistance connected between said electrodes B1 and B2, the magnitude of said voltage V2 corresponding to the magnitude of said load resistance.   
     
     
       3. A device as defined in claim 1 further comprising: a circuit T connected between said electrodes A1 and A2, said circuit T including means for providing an alternative current pulse power as a power of said voltage V1 and controlling a pulse width and a pulse repetition frequency of said alternative current pulse power, and means for controlling the value of said voltage V1.   
     
     
       4. A device as defined in claim 1 said voltage V2 is larger than said voltage V1. 
     
     
       5. A device as defined in claim 3 wherein said circuit T comprises an oscillator circuit consisting of a positive feedback amplifier circuit and a resonance circuit connected to said amplifier circuit, said resonance circuit including said piezoelectric ceramic as a resonance element, said amplifier circuit being connected between said electrodes A1 and A2. 
     
     
       6. A device as defined in claim 5, wherein said amplifier circuit including a power amplification circuit and a phase-sensing circuit, an output power of said power amplification circuit being applied through said electrodes A1 and A2, said phase-sensing circuit detecting a phase of a current through said electrodes A1 and A2, said power amplification circuit amplifying a power of an amplified signal of said phase of said current detected by said phase-sensing circuit, said power amplification circuit including a transistor as a terminal amplifier element and a coil for raising a voltage in a passage for applying said transistor with a direct current. 
     
     
       7. A device as defined in claim 6, wherein said phase-sensing circuit comprises a first diode connected in series to said electrodes A1 and A2 and a second diode connected in parallel to said first diode with the opposite polarity to said first diode. 
     
     
       8. An ultrasonic device for transducing an electric signal comprising: a piezoelectric ceramic with a cubic shape, said piezoelectric ceramic having two end surfaces, ZA and ZB, running perpendicular to the polarization axis of said piezoelectric ceramic;   means for transducing an electric signal consisting of a first transducer element comprising at least two electrodes A1 and A2 forming an input pair, and a second transducer element comprising at least two electrodes B1 and B2 forming an output pair;   a load resistance connected between said electrodes B1 and B2;   a circuit T connected between said electrodes A1 and A2 comprising an oscillator circuit consisting of a positive feedback amplifier circuit and a resonance circuit connected to said amplifier circuit, said resonance circuit including said piezoelectric ceramic as a resonance element, said amplifier circuit being connected between said electrodes A1 and A2,   said electrodes A1 and A2 being formed on said surface ZA such that said electrodes A1 and A2 are not connected to each other and are separated by a line dividing the area of said surface ZA nearly at the rate of 1 to 1 and parallel to one side of said surface ZA, said surface ZB facing to said surface ZA,   said electrodes B1 and B2 being formed on said surface ZB such that said electrodes B1 and B2 are not connected to each other and are separated by a line dividing the area of said surface ZB nearly at the rate of 1 to 1 and parallel to one side of said surface ZB,   said piezoelectric ceramic, said electrodes A1, A2, B1 and B2 forming a piezoelectric vibrator,   said first transducer element receiving a high-frequency electric signal S1 with a voltage V1 from said circuit T, and causing said piezoelectric vibrator to vibrate at a frequency, almost the same as the resonance frequency of said piezoelectric ceramic,   said second transducer element transducing the acoustic vibration of said piezoelectric vibrator to an electric signal S2 with a voltage V2 having almost the same frequency as said resonance frequency, and delivering said electric signal S2 outside, the magnitude of said voltage V2 corresponding to the magnitude of said load resistance.   
     
     
       9. A device as defined in claim 8, wherein said circuit T includes means for providing an alternative current pulse power as a power of said voltage V1 and controlling a pulse width and a pulse repetition frequency of said alternative current pulse power, and means for controlling the value of said voltage V1. 
     
     
       10. A device as defined in claim 8, wherein said voltage V2 is larger than said voltage V1. 
     
     
       11. A device as defined in claim 8, wherein said amplifier circuit including a power amplification circuit and a phase-sensing circuit, an output power of said power amplification circuit being applied through said electrodes A1 and A2, said phase-sensing circuit detecting a phase of a current through said electrodes A1 and A2, said power amplification circuit amplifying a power of an amplified signal of said phase of said current detected by said phase-sensing circuit, said power amplification circuit including a transistor as a terminal amplifier element and a coil for raising a voltage in a passage for applying said transistor with a direct current. 
     
     
       12. A device as defined in claim 11, wherein said phase-sensing circuit comprises a first diode connected in series to said electrodes A1 and A2 and a second diode connected in parallel to said first diode with the opposite polarity to said first diode. 
     
     
       13. An ultrasonic device for transducing an electric signal comprising: a piezoelectric ceramic with a cylindrical shape such that the ratio of lengths between diameter and longitudinal directions is nearly equal to 1, said piezoelectric ceramic having two end surfaces, ZA and ZB, running perpendicular to the polarization axis of said piezoelectric ceramic;   means for transducing an electric signal consisting of a first transducer element comprising two electrodes A1 and A2 forming an input pair, and a second transducer element comprising three electrodes B1, B2 and B3, said electrodes B1 and B2, or said electrodes B2 and B3 forming an output pair; and   a circuit T connected between said electrodes A1 and A2 comprising an oscillator circuit consisting of a positive feedback amplifier circuit and a resonance circuit connected to said amplifier circuit, said resonance circuit including said piezoelectric ceramic as a resonance element, said amplifier circuit being connected between said electrodes A1 and A2,   said electrodes A1 and A2 being formed on said surface ZA such that said electrodes A1 and A2 are not connected to each other,   said electrodes B1, B2 and B3 being formed on said surface ZB such that said electrodes B1, B2 and B3 are not connected to each other,   said piezoelectric ceramic, said electrodes A1, A2, B1, B2 and B3 forming a piezoelectric vibrator,   said first transducer element receiving a high-frequency electric signal S1 with a voltage V1 from said circuit T, and causing said piezoelectric vibrator to vibrate at a frequency, almost the same as the resonance frequency of said piezoelectric ceramic,   said second transducer element transducing the acoustic vibration of said piezoelectric vibrator to an electric signal S2 with a voltage V2 having almost the same frequency as said resonance frequency, and delivering said electric signal S2 outside through said electrodes B1 and B2, or through said electrodes B2 and B3.   
     
     
       14. A device as defined in claim 13, wherein said electrodes A1 and A2 are separated each other by a line dividing the area of said surface ZA into two parts, and said electrodes B1, B2 and B3 are separated each other by two lines dividing the area of said surface ZB into three parts. 
     
     
       15. A device as defined in claim 13, wherein said circuit T includes means for providing an alternative current pulse power as a power of said voltage V1 and controlling a pulse width and a pulse repetition frequency of said alternative current pulse power, and means for controlling the value of said voltage V1. 
     
     
       16. A device as defined in claim 13 wherein said voltage V2 is larger than said voltage V1. 
     
     
       17. A device as defined in claim 13 further comprising: a first load resistance connected between said electrodes B1 and B2, the magnitude of said voltage V2 corresponding to the magnitude of said first resistance; and   a second load resistance connected between said electrodes B2 and B3, the magnitude of said voltage V2 corresponding to the magnitude of said second resistance,   
     
     
       18. A device as defined in claim 13, wherein said amplifier circuit including a power amplification circuit and a phase-sensing circuit, an output power of said power amplification circuit being applied through said electrodes A1 and A2, said phase-sensing circuit detecting a phase of a current through said electrodes A1 and A2, said power amplification circuit amplifying a power of an amplified signal of said phase of said current detected by said phase-sensing circuit, said power amplification circuit including a transistor as a terminal amplifier element and a coil for raising a voltage in a passage for applying said transistor with a direct current. 
     
     
       19. A device as defined in claim 13, wherein said phase-sensing circuit comprises a first diode connected in series to said electrodes A1 and A2 and a second diode connected in parallel to said first diode with the opposite polarity to said first diode.